Hi everyone,
I've just found this site, hopefully it can help with the problem I'm having.

I was messing around with my calibre and managed to import a number of .mobi files that are zero bytes in size. They now appear in my calibre database. Does anyone have a good way of removing them from the command line.

Zynster; when I read the help for calibredb remove it tells me it expects another argument; a comma separated list of IDs of books to remove; NOT a list on stdin of books to process, so I would not have expected that to work at all.

You could also just have dropped the zero byte files at the OS level and then performed a library check function to identify the missing material in calibre and then had calibre peform a cleanup.

Also, in the calibre gui, did you try a search for
size:=0 format:mobi
then select all the displayed records, right click them and do either a remove books | remove selected books OR a remove books | remove remove files of a specified format and select mobi?